Derailleur

ABSTRACT

The present invention is a derailleur for moving a chain to a different sized sprocket in a drive sprocket nest comprising: a feed arm for directing onto one of multiple sprockets within the drive sprocket nest when the feed arm is rotatably mounted at a pivot end onto a frame of a vehicle; a take up roller attached to the feed arm supporting the chain so that when the take-up roller moves laterally the chain moves from one sprocket to another sprocket in the drive sprocket nets; a roller feel sprocket supporting the chain so that the chain contacts over ½ the perimeter of the sprocket contacting the chain in the drive sprocket nest; an opposite chain guide end attached to the feed arm so that the chain guide end traces a path substantially parallel to a tangent to the outer periphery of the drive sprocket nests.

CLAIM OF PRIORITY

This application is a continuation in part of co-pending U.S.application Ser. No. 12/898,817 filed on Oct. 6, 2012 entitledDERAILLEUR.

TECHNICAL FIELD

This application relates to a speed changing device for rider propelledvehicles using a chain drive and a sprocket nest with a plurality ofdifferent sized sprockets. The sprocket changing device is a pivotingderailleur system with a derailleur and a chain slack take-up mechanism.

BACKGROUND OF THE INVENTION

The derailleur system currently used in bicycles has been adequatelyengineered to allow the chain to smoothly move to an adjacent sprocketat selected locations around each sprocket. Each sprocket is modified toprovide clearance for chain shifting with a small plurality of reducedsize chain pickup teeth with modified shape at selected locations on thesprocket, but with adjacent normally sized teeth providing adequatechain grip and strength around the rest of the sprocket's outerperiphery or circumference.

The chain travel is directed by a movement of the derailleur guiding thechain from the sprocket it is on and feeding the chain onto an adjacentlarger sprocket when decreasing the speed or a smaller sprocket whenincreasing the speed.

The bicycle derailleur devices are physically mounted on the frame ofthe bicycle and its movement is generally operated by a guide wire orcable extending from a shifting lever attached on the handle bar to thederailleur. When the rider selects a new sprocket, he moves the levermoving the wire or cable which in turn repositions the derailleur toeffect a sprocket change. The derailleur is a sophisticated device thathas a fixed structure attached to the frame or rear axle and a movablestructure that is held in position by at least one double pivot withmultiple heavy duty springs that allow the movable elements to rotate ormove in the path of a parallelogram created by two opposing plateshinged to move parallel relative to the other. This movement enables thechain guide portion of the derailleur to move relative to the sprocketnest in a relatively uniform path in relation to the guide and thesprockets while minimizing twisting the chain.

In order to function properly, the chain slack that exists when thechain is on the sprocket must be taken up. The amount of chain slack isreduced as the chain moves to larger sprockets. In bicycles, thederailleur chain guide system is positioned to extend well below theaxle and frame. This enables the chain to serpentine through the lowhanging derailleur guide system by having the chain extend well belowthe largest of the sprockets.

These prior art derailleur devices allow the chain to be moved along thevarious sized sprockets with relative ease. In U.S. Pat. No. 7,780,558entitled “Bicycle Rear Derailleur” assigned to Shimano Inc.; a ratherdetailed description is provided of these rather sophisticated devicesfor changing sprockets on a bicycle. Shimano is a world leader in themanufacture of derailleurs and is known for providing some of the bestdevices for changing sprockets on chain driven bicycles. Their rearderailleurs are engineering marvels exhibiting good reliability anddurability.

These excellent products, however, because they are so well made withmuch sophistication are costly. A need exists to provide a simpler, lesscomplex derailleur design that is reliable and durable.

Recently, a new generation of scooters and bicycles has been developedwith reciprocating foot pedals. These vehicles, particularly thescooters, have frames that have a very low center of gravity to make thevehicles more stable. The frames are so low to the ground that the priorart derailleurs conventionally positioned below the rear sprocket nestare virtually useless. Nevertheless, these vehicles need a shiftingdevice to allow the rider to selectively change speeds.

It is therefore an objective of the present invention to provide aderailleur type device and chain slack take-up assembly that does notextend into the ground clearance of the vehicle. It was a furtherobjective of the present invention to provide a reliable and lesscomplex device that can be manufactured at an affordable cost.

It was still another objective of the present invention to provide aderailleur device with a large range of motion to facilitate the rangeof rear sprocket sizes in a single rear sprocket nest equivalent topresent bicycle derailleurs.

Another objective of the invention is to have the chain feed to thederailleur chain take-up directed so as to be fed close to thecenterline of the drive sprocket.

These and other features of the derailleur system of the presentinvention are described as follows.

SUMMARY OF THE INVENTION

A derailleur, for moving a chain to different sized sprockets arrangedsmall to large in a sprocket nest is disclosed. The derailleur has afeed arm for directing the chain onto one of multiple sprockets withinthe sprocket nest. The feed arm is rotatably mounted at a pivot end onan angular pivot and when the feed arm rotates on the pivot an oppositechain guide end of the feed arm traces a path substantially parallel toa tangent to the outer periphery of the sprocket nest. The movement ofthe feed arm is mechanically driven by a user command and is preferablymoved by a connected rod, wire or cable. The guide end of the derailleurhas a chain guide, wherein the chain guide can be a smooth surface or aroller or toothed roller. The derailleur further has a chain slacktake-up assembly having a pivotal take-up idler arm for chain slacktake-up, which is pivotably connected to the chain guide end of the feedarm. Preferably, the feed arm and the pivotal take-up idler arm share achain guide wherein the feed arm and idler arm are both spring loaded,preferably sharing the same spring wherein one spring biases both thefeed arm and idler arm, the spring being connected to the idler arm andonto the angular pivoting feed arm.

One end of the spring is connected to the feed arm at or near the framepivot, the opposite end of the spring is connected to the idler arm on apin eccentric to the pivot biasing the idler arm providing the chainslack take-up, wherein the chain feed arm and take-up idler armassemblies lie within a space between the driver sprocket and drivensprocket nest, the space defined as the area between the major diametersprocket of the driver sprocket and driven sprockets.

A chain take-up assembly has a pivotal idler arm for taking up chainslack, the idler arm having a pair of chain guides, one being a feedguide, the other a take-up guide, at opposite ends to serpentine thechain through the guides; and a spring, pulling the idler arm tomaintain chain tension; and wherein the excess chain slack is stored inthe space between the driver and driven sprockets.

The assembly allows the chain to straighten when positioned on thelargest sprocket pairs. The chain take up assembly lies within a spacebetween the driver sprocket and driven sprocket nest, the space definedas the area between the major diameter sprocket of the driver sprocketand driven sprockets. The chain guides are smooth surfaces or rollerswith or without teeth.

The present invention can include a derailleur for moving a chain to adifferent sized sprocket in a drive sprocket nest comprising: a feed armfor directing onto one of multiple sprockets within the drive sprocketnest when the feed arm is rotatably mounted at a pivot end onto a frameof a vehicle; a take up roller attached to the feed arm supporting thechain so that when the take-up roller moves laterally the chain movesfrom one sprocket to another sprocket in the drive sprocket nets; aroller feel sprocket supporting the chain so that the chain contactsover ½ the perimeter of the sprocket contacting the chain in the drivesprocket nest; an opposite chain guide end attached to the feed arm sothat the chain guide end traces a path substantially parallel to atangent to the outer periphery of the drive sprocket nests.

The take up roller can support the chain so that the chain contacts over½ the perimeter of a pedal sprocket. The feed arm can cause the chain tomove from a first pedal sprocket to second pedal sprocket once the chainis at the smallest sprocket of the drive sprocket nest so that the chaincan be moved about the drive sprocket nest and the pedal sprocket withone derailleur. The feed arm causes the chain to move from a first pedalsprocket to second pedal sprocket once the chain is at the largestsprocket of the drive sprocket nest so that the chain can be moved aboutthe drive sprocket nest and the pedal sprocket with one derailleur.

The movement of the feed arm can be moved by tensioning a first cableconnected to the feed arm causing the take up roller to move in alateral direction relative to a long axis of the frame of the vehiclecausing the chain to move from one sprocket to another in the drivesprocket nest. The movement of the roller feed sprocket can be actuatedby tensioning a second cable connected to the feed arm causing theroller feed sprocket to move in a lateral direction relative to a longaxis of the frame of the vehicle causing the chain to move from onesprocket to another in a pedal sprocket nest.

The excess slack in the chain can be is taken up in a slack area definedby a horizontal tangent of the top perimeter of a pedal sprocket and alargest sprocket in the drive sprocket nest and a horizontal tangent ofthe bottom perimeter of a pedal sprocket and a largest sprocket in thedrive sprocket nest. The slack area can be further defined by ahorizontal tangent of the top perimeter of a largest sprocket of a pedalsprocket nest and a largest sprocket in the drive sprocket nest. Theslack area can be further defined by a vertical tangent on a forwardpoint of the largest sprocket of the sprocket nest and a verticaltangent on a rearward point of a pedal sprocket. The pivot end can becarried by the frame forward an axis defined through the drive sprocketnest.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a bicycle with a prior art rear derailleurfor a bicycle shown.

FIG. 2 is a side view of a bicycle with reciprocating pedals with thederailleur of the present invention shown in the large sprocketposition.

FIG. 3 is perspective view of the derailleur assembly with a chain slacktake-up assembly oriented in the large sprocket feed position.

FIGS. 3A and 3B are a top view and a side view taken from FIG. 3.

FIG. 4 is an exploded view of the derailleur assembly of FIG. 3.

FIG. 5A is a partial plan view of the chain and derailleur wherein thesmall rear sprocket is engaged with the chain shown in dashed lines.

FIG. 5B is the schematic view of FIG. 5A, but with the large sprocketengaged with the chain shown in dashed lines.

FIG. 6 is an alternative embodiment derailleur assembly with a hubprojection to allow pivot rotation in excess of 180 degrees.

FIG. 7 is another alternative embodiment for over 180 degrees rotationof the derailleur with a lanced spring support.

FIG. 8 is a view of a top swivel connector for the spring.

FIGS. 9A, 9B and 9C are diagrammatic bottom views of the derailleurassembly showing the position of the feed chain path and the idlersprocket when the small, medium and large nest sprockets are engaged.The top portion of the chain is not shown for clarity.

FIGS. 10A, 10B and 10C are schematic views of the rear sprocket nest andfront drive sprocket and the space between the sprockets in which thederailleur moves;

FIG. 11 is a schematic view of a rear sprocket and front drive sprocketand the space between the sprockets in which the derailleur can bedisposed; and,

FIG. 12 is a schematic view of aspects of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a side view of a prior art single derailleur assembly 202moved by a shift mechanism 206 and guide cable 209 at the handle bar 208used on a bicycle 200. As can be seen the device is attached to the rearwheel hub and therefore positioned well below the rear wheel sprocketnest 201. This enables the chain 204 to extend from the forward drivesprockets 203 rearwardly with the chain 204 forming two almost parallelstraight lines to the rear wheel 205 sprocket nest 201 and derailleurassembly 202. The derailleur assembly 202 is shown directly under thecombination of the rear sprocket nest 201 and the rear axle 207 whichmeans the lower part of chain 204 is positioned close to the ground asshown, but well above the lowest point on the pedal 210.

The revolution of the pedals 210 is a continuous 360 degree movementwith the lowest point of the pedal stroke clearing the ground by severalinches, thus providing adequate ground clearance during a severe leaningturn.

With reference to FIG. 2, a reciprocating pedal bicycle 100 isillustrated. The bicycle has a low slung frame 110 with a pair ofreciprocating foot pedals 102 that move up and down to provide forwardpropulsion. The ground clearance on both the frame and the bottom strokeof the foot pedals 102 is a mere few inches in some models. The reasonfor the low center of gravity is a desire to maintain superior ridestability with reduced rider's ability requirements. Those bicycles andin some versions, scooters can achieve excellent speeds which are bestaccomplished with the use of a gear shifting mechanism. As is readilyapparent, conventional low hanging derailleur assemblies simply woulddrag on the ground unless the ground clearance was raised, sacrificingride stability and the ability to design a low frame with a frame bottomadapted to ride down railings similar to techniques used inskateboarding.

To overcome this problem, an improved concept in gear shifting designwas required that still utilized an existing gear shift mechanism 106mounted on the handle bar 108 and a single shift cable 109.

As shown in FIG. 2, and in greater detail in FIG. 3, a derailleurassembly 10 with a chain slack take-up assembly 20 is illustrated. Alow-hung system such as scooters can not use a guide system thatrequires major clearance between the driven wheel center and ground,however, a system that utilizes the space beneath the top driving linksof chain and above a line between the bottom of the largest nestsprocket 101 L and the bottom of the largest forward drive sprocket 103.As illustrated, the entire derailleur assembly 10 is located between thespace of the largest or major diameter rear sprocket 101L of thesprocket nest 101 and the major diameter of the forward drive sprocket103. Accordingly, an upper line and a lower line drawn between thesemajor diameter forward and rear sprockets is all the space needed forthe chain take-up and derailleur assemblies. As shown, the derailleurassembly 10 does not occupy the ground clearance space as required inthe prior art devices, but rather is packaged between the pair of majordiameter sprockets. This is a significant breakthrough in gear shiftmechanisms because it dramatically reduces the vertical space requiredfor the chain. The design is useful not only in low hung vehicles, butin any bicycle. Consider how many derailleurs have been bent or brokenwhen they hit a rock or downed tree when mountain biking This moreprotected position of the derailleur assembly 10 of the presentinvention dramatically reduces this type of risk.

As shown in FIGS. 3, 3A,3B and 4, the basic element of the derailleurassembly is a pivot arm 11 located on a pin 12 fixed to the frame 110 orotherwise affixed to a bracket for mounting onto the frame 110 at anangle relative to the change sprocket assembly or rear sprocket nest101. The upper end of the pivot arm supports a guide roller 30 as wellas the upper end of the take-up idler arm 20 with a take-up roller 40 atthe bottom opposite end of the take-up idler arm 20. The pivot pin 12being at an angle tends to promote chain twist, but the sprocketsthemselves limit that motion to allow smooth change of position. Each ofthe roller sprockets 30 and 40 as shown has a small amount of gapbetween the take-up frame sides 21, 22 holding them which allow therollers to 30 and 40 to shift slightly to reduce the amount of chaintwist.

As shown in FIG. 4 the rollers 30 and 40 are held between the framesides 21,22 through openings 24,25 by threaded fasteners 19A,19B with asmall tubular bearing 18 that acts as the bearing in the openings 31,41of the sprockets 30,40, respectively. Fastener 19A has a longer threadedend for securing the take-up idler arm 20 at the tapped opening 14. Theshift cable 109 is to be attached in the hole or opening 15. As furthershown the guide feed arm 11 has a bent over portion 16 with a pivot hole17 into which fits a tubular bearing sleeve 12A mounted on the pivot pin12. A single spring 50 is shown that is connected at one end 51 to abent over tab 19 at the bottom end of the guide feed arm 11 and isfurther connected at an opposite end 52 onto a stop pin 26 on thetake-up idler arm 20.

In FIG. 5A and as is schematically shown in FIG. 10A (reversed lookingfrom the opposite side), when a small sprocket 101S is selected, a longsection of chain 60 must be stored in a back-and forth configurationadjacent to or beside the derailleur sprocket nest 101. In FIG. 5B andschematically in FIG. 10B but similarly reversed, when a large sprocket101L is selected, the pivot arm angle allows the guide roller to dropand receive the chain in almost straight line from the drive sprocket103.

A single spring 50 connected to the guide arm 11 and the angled pivotidler arm 20 supplies all the motion and take-up requirements for thesystem. When a chain 60 shift between small diameter sprockets in thesprocket nest is initiated, the chain 60 and the guide arm 11 are movedsideways out of line with the top driving section of chain to avoidinterfering between chain sections moving in opposite directions.

Referring back to FIGS. 3B and 4, the pin 12 is shown attached to amounting bracket 13 which is to be attached by welding or otherwisefixed to the frame 110. The mounting bracket can be attached to thebottom of the frame, the side of the frame or the top of the frame. Thebase of the bracket 13 aligns with the frame 110, and the pin 12 isprojecting at an angle to the inclined surface of the bracket 13. Theinclined surface is oriented at an angle θ relative to the frame 110 asillustrated in FIGS. 9A,9B, and 9C. The angle θ should be equal to thetangent slope of the sprocket nest 101, as shown in FIGS. 9A, 9B and 9C,the angle θ was 30 degrees. The angled guide arm 11 fits over the pin 12and is rotatable about the pin 12 while it translates back and forth toline up with the sprockets in the nest 101, and thus the guide arm 11rotates forward and translates sideways. As shown in FIG. 11, oneembodiment includes the mounting plate disposed along a plane generallyorthogonal to the axis of the roller sprockets.

The angled guide arm 11 as shown has a projecting tab 9 with a hole 15for securing the gear shifting rod or wire 109. The tab 9 is located inclose proximity to the pivot pin 12 to exactly duplicate the controlwire motion of a conventional derailleur on bicycles. The guide arm 11is twisted about 30 degrees so that the orientation of the chain 60passing through the guide rollers 30 and 40, shown as shallow toothedsprocket rollers, is substantially parallel to the drive sprockets andthe rear sprockets of the nest 101.

Referring to FIGS. 10A, 10B and 100, the single spring 50 connected nearor at the pivot 12 provides torque through the chain take-up idler arm20. When the chain 60 is on the major diameter rear sprocket 101 L, thespring provided torque is modest but when the guide arm 11 arm rotatesto the smaller sprocket 101S, the single spring 50 is stretched but actsover a shorter distance to provide torque. This means as the derailleur10 is shifted upward through the gears, the spring 50 assist in themovement of the derailleur assembly 10 and insures the slack in thechain 60 is fully taken out by the chain take-up idler arm 20.

Particular attention in FIG. 10C is called to the chain 60 when movedonto the smallest rear sprocket 101S. In this position, the derailleur10 is orientated such that the chain 60 can encircle substantially morethan 180 degrees around the sprocket 101S. As shown, almost 240 degreesof the smallest sprocket 101S is engaged by the chain 60. This featureis very beneficial in that the wrapping of the chain enables moresprocket teeth to be engaged. In a conventional low hung derailleur, 180degrees of engagement is the best to be hoped for; and typically lessthan 180 degrees is experienced. The device according to this presentinvention enables far more teeth to be engaged. This means that even asmaller sprocket diameter can be used increasing the range of gearratios available in a single nest.

As further illustrated in FIG. 9B, the idler arm 20 is modified suchthat its orientation is centered or aligned with the middle sprocket101M, but as shown in FIGS. 9A and 9C, is slightly canted at eitherextreme major or minor diameter sprockets at the roller feed end Fsprocket 30 and the idler I sprocket 40 of the chain 60. This creates aslight twist in the chain 60, but because the guide rollers 30 and 40have a gap or clearance when mounted in their respective frame sides 21,22 in which they are held, they move laterally allowing the twist tostraighten out relative to the sprocket to which it is attached. Thisalong with the fact the single spring 50 provides less torque at boththe top and the bottom of its range permits the chain 60 to straightenout. In one embodiments, the take up roller remains centered while thesprocket selector roller is slightly canted either at the extreme majordiameter or minor diameter of the roller feed end.

Conventional derailleurs use massive spring force and therefore requireprecise parallel alignment. The derailleur 10 according to the presentinvention is greatly simplified in its design and thus can easilyaccommodate this small amount of chain twist. This assumes of course theadequate distance is provided between centers of the forward drivesprocket 103 and the rear stacked sprocket nest 101, for example atleast 10 inches, preferably 11 inches for a 0.5 inch bicycle chain and asix sprocket nest. This for a six speed derailleur allows a sufficientlength of chain 60 to allow the twist angle to be small enough tostraighten out due to the flexibility of standard bicycle chain.

A unique feature of this new derailleur design is that it can be usedwith a nested and stacked rear sprocket nest combined with a multipleforward drive sprocket nest and is capable of chaining not only the reargears, but the forward gears as well. Presently, two conventionalderailleurs are required to develop adequate speed change on bicycles.The single spring tension of the present derailleur 10 of the presentinvention allows it to move the chain at both locations. While this hasobvious cost benefits, it is believed the present inventions use ofmultiple forward sprockets is not providing the benefit for the costrequired. This is true because of the duplication of gear ratiosavailable means little or no real advantage is achieved.

A 27 speed derailleur system on a bicycle with rotating pedals actuallyprovides about 8 distinct speeds with multiple redundant combinationsrequiring two sets of derailleur devices providing the intermediatespeeds. The present invention derailleur 10 can provide a singlelocation with a wider gear tooth range to equal the total gear ratio ofa two derailleur bicycle system without the redundancy, reduced stressand wear of the multiple rear sprocket set and safer chain safety nearthe pedals.

The prior art has a 27 speed with a three sprocket nest at the pedaldriving one of 9 rear wheel sprockets at the rear wheel derailleurpositions providing duplicate intermediate speeds. The derailleur 10 ofthis invention offers a compact single control derailleur system withoutredundancy with equal step up ratios between speeds. This providesreduced stress and wear on the sprockets due to greater wrap around forsmall sprockets and greater safety near the pedals when a single chainlocation must be guarded instead of a 3 chain wide protected area.

The earlier described derailleur of FIGS. 1 through 5B has the normaltension spring action and stops on the guide arm 11 to stop the pin 26set to produce rotation of the pivot arm about a pivot limited less than180 degrees rotation. When additional rotation is required, a hubprojection 80 about or near the pivot can be located to rest against thespring coils and prevent or limit the tension spring coils from reachingthe center of rotation of the pivot arm, as shown in FIG. 6. In thiscase one of the limit stops on the guide arm 11 can be moved oreliminated. This effect was demonstrated on a scooter derailleur system.Wherein the correct selection of pivot projection in the shape of acylindrical hub 80 with an appropriately sized cylinder diameter allowedthe rotation to go well past the 180 degree rotation to well over 240degrees represented as angle .alpha. This increased rotation can bedesigned to fit the need.

This rotation over 180 degree for an arm with a single tension springdrive provides several alternate configurations. The equivalence of thecylindrical hub to develop over 180 degrees rotation of a spring returntension spring arm as shown in FIG. 6 can be achieved by lancing asegment 90 of sheet metal adjacent to the hub or pivot and form it toproject outwardly and act as a guide supporting the spring smoothlyagainst the side coils of the tension spring, as shown in FIG. 7represented by the angle .beta.

As shown in FIG. 8A, tension spring top swivel connector 86 may be builtas a tube 86 with the ID swivel on a shaft or the pin 26 and the ODmodified with a groove 88 to prevent the end twist loop of tensionspring from falling off on a spring groove at the spring contact area.

As shown, the entire derailleur assembly 10 can occupy and functionbetween the space defined as a pair of tangent lines between majordriven and major diameter nest sprockets. However, it is important tonote the ground clearance needed simply requires the derailleur andtake-up assembly to occupy a space between the horizontal tangent linesof the largest sprocket diameters.

Furthermore, as shown in FIGS. 9A, 9B and 9C the rear sprocket nest hasa conical linear tangency shown as straight but preferably, can be madehaving a non-linear tangency or a curved peripheral profile. In such acase, the straight line angle formed between the largest sprocket andthe smallest sprocket can be used to set the pivot pin angle. This meansthe distance between the derailleur feed sprocket 30 and the differentsized sprockets will vary. This variation can be accommodated withoutdetriment due to the sole requirement of feeding the chain 60 onto aspecific sprocket.

It is understood that because the system moves along a fixed angle setby the pivot, the sweep angle of the derailleur lies in a curved plane,accordingly the invention relies on a movement that uses this fact toset the appropriate variable distances between the derailleur guide feedroller sprocket 30 and the individual sprockets of the sprocket nest101. Adjustment of these different aspects of the invention can bevaried.

Referring for FIG. 12, in one embodiment, mounting plate 13 is disposedalong a plane generally parallel to the axis of the roller sprockets 20and 30 and parallel to frame 110. As shown, the mounting plate isattached to the bottom of the frame. In one embodiment, the mountingbracket can be attached to the top or side of the frame. The spring is acoil spring 300 with one end attached generally in the center of thetake up idler arm and the other end attached to a connecting plate 302.The connecting plate is rotatably attached to the idler arm 20 andattachment idler arm spring attachment point 304. The connecting platecan include an angled portion 308 so that when the idler arm is moved,the roller sprockets move in a lateral direction in relation to a longaxis of the frame causing the chain to move from sprocket to sprocket.The connector plate can also include angled potion 316 to properlyposition the guide arm.

An idler arm guard 310 can in attached to the connecting plate to assistin in preventing the connecting plate from interfering with movement byguiding the connecting plate along the mounting plate and frame. Cable312 a can be connected at cable connection point 314 a so that whentension in applied to the cable the idler arm moves effecting the chain.In one embodiment, cable 312 b can be attached a cable attachment point314b.

When the mounting plate is attached to the top of the frame, the upperroller sprocket can be disposed above the axis of the drive axle or rearwheel axle so that the derailleur is disposed in the shifting area. Thelower roller can be disposed below the axis of the drive sprocket orrear wheel. Further, the cable can cause the upper roller to moveorthogonal to the long axis of the frame by either pulling the guide armforward or in one embodiment, rearward.

Variations in the present invention are possible in light of thedescription of it provided herein. While certain representativeembodiments and details have been shown for the purpose of illustratingthe subject invention, it will be apparent to those skilled in this artthat various changes and modifications can be made therein withoutdeparting from the scope of the subject invention. It is, therefore, tobe understood that changes can be made in the particular embodimentsdescribed which will be within the full intended scope of the inventionas defined by the following appended claims.

What is claimed is:
 1. A derailleur for moving a chain to a differentsized sprocket in a drive sprocket nest comprising: a feed arm fordirecting onto one of multiple sprockets within the drive sprocket nestwhen the feed arm is rotatably mounted at a pivot end onto a frame of avehicle; a take up roller attached to said feed arm supporting the chainso that when said take-up roller moves laterally the chain moves fromone sprocket to another sprocket in the drive sprocket nets; a rollerfeed sprocket supporting the chain so that the chain contacts over ½ theperimeter of the sprocket contacting the chain in the drive sprocketnest; an opposite chain guide end attached to said feed arm so that saidchain guide end traces a path substantially parallel to a tangent to theouter periphery of the drive sprocket nests.
 2. The derailleur of claim1 wherein said take up roller supports the chain so that the chaincontacts over ½ the perimeter of a pedal sprocket.
 3. The derailleur ofclam 1 wherein said feed arm causes said chain to move from a firstpedal sprocket to second pedal sprocket once said chain is at thesmallest sprocket of said drive sprocket nest so that the chain can bemoved about said drive sprocket nest and said pedal sprocket with onederailleur.
 4. The derailleur of clam 1 wherein said feed arm causessaid chain to move from a first pedal sprocket to second pedal sprocketonce said chain is at the largest sprocket of said drive sprocket nestso that the chain can be moved about said drive sprocket nest and saidpedal sprocket with one derailleur.
 5. The derailleur of claim 1 whereinsaid movement of said feed arm is moved by tensioning a first cableconnected to said feed arm causing said take up roller to move in alateral direction relative to a long axis of the frame of the vehiclecausing the chain to move from one sprocket to another in the drivesprocket nest.
 6. The derailleur of claim 1 wherein said movement ofsaid roller feed sprocket is moved by tensioning a second cableconnected to said feed arm causing said roller feed sprocket to move ina lateral direction relative to a long axis of the frame of the vehiclecausing the chain to move from one sprocket to another in a pedalsprocket nest.
 7. The derailleur of claim 1 wherein said excess slack inthe chain is taken up in a slack area defined by a horizontal tangent ofthe top perimeter of a pedal sprocket and a largest sprocket in saiddrive sprocket nest and a horizontal tangent of the bottom perimeter ofa pedal sprocket and a largest sprocket in said drive sprocket nest. 8.The derailleur of claim 7 wherein said slack area is defined by ahorizontal tangent of the top perimeter of a largest sprocket of a pedalsprocket nest and a largest sprocket in said drive sprocket nest.
 9. Thederailleur of claim 1 wherein said slack area is defined by a verticaltangent on a forward point of the largest sprocket of said sprocket nestand a vertical tangent on a rearward point of a pedal sprocket.
 10. Thederailleur of claim 1 wherein said pivot end is carried by the frameforward an axis defined through said drive sprocket nest.
 11. Aderailleur for moving a chain to a different sprockets in a drivesprocket nest and different sprockets in a pedal sprocket nestcomprising: a feed arm; a take up roller rotatably carried by said feedarm supporting the chain so that said chain contacts over ½ theperimeter of a sprocket within said drive sprocket nest; a first cableconnected to said feed arm so that when said first cable is tensioned,said take roller causes the chain to move from one sprocket to anotherin said drive sprocket nest; a roller feed sprocket rotatably carried bysaid feed arm; a second cable connected to said feed arm so that whensaid second cable is tensioned, said roller feed sprocket causes thechain to move from one sprocket to another in said pedal sprocket nest.12. The derailleur of claims 11 including a guide end attached to saidfeed arm so that said chain guide end traces a path substantiallyparallel to a tangent to the outer periphery of the drive sprocketnests.
 13. The derailleur of claim 11 wherein excess slack in the chainis disposed in an area defined by a horizontal tangent of the topperimeter of a pedal sprocket and a largest sprocket in said drivesprocket nest and a horizontal tangent of the bottom perimeter of apedal sprocket and a largest sprocket in said drive sprocket nest. 14.The derailleur of claim 11 wherein said derailleur is disposed in aderailleur area defined by a vertical tangent at a rearward point of alargest sprocket of said pedal sprocket nest, horizontal tangent of thetop perimeters of the largest sprockets of the pedal and drive sprocketnest, vertical tangent at the forward point of the perimeter of thelargest sprocket of said drive sprocket nest and horizontal tangent ofthe bottom perimeter of the largest sprockets of the pedal and drivesprocket nests.
 15. The derailleur of clam 11 wherein the roller feedsprocket forces the chain upwards so that the chain contacts over ½ theperimeter of a pedal sprocket.
 16. A chain take-up assembly comprising:a pivotal idler arm for taking up chain slack, the idler arm having apair of chain guides at opposite ends to serpentine the chain throughthe guides; and a spring, pulling the idler arm to maintain chaintension; and wherein the excess chain slack is stored in any spacebetween the drive sprocket nest and the pedal sprocket nest.
 17. Thechain take-up assembly of claim 16 wherein the assembly allows the chainto untwist when positioned on the largest sprocket pairs.
 18. The chaintake-up assembly of claim 16 wherein the chain guides are smoothsurfaces.
 19. The chain take-up assembly of claim 16 wherein the chainguides are toothed rollers.
 20. The chain take-up assembly of claim 16include a cable attached to said idler arm to move said idler armcausing said chain to move from sprocket to sprocket in the drivesprocket nest and pedal sprocket nests.